Compositions containing hollow microspheres

ABSTRACT

A composition is described with comprises a mixture of 
     (A) from about 5% to about 60% by weight of at least one water-insoluble polymer; 
     (B) from about 1% to about 30% by weight of inorganic or synthetic resinous hollow microspheres; and 
     (C) from about 20% to about 85% of at least one volatile organic liquid which is a solvent for the polymer of (A). 
     The compositions also may contain (D) at least one solid particulate inorganic filler. Adhesive compositions such as solvent cements prepared in accordance with the present invention are characterized as low VOC compositions wherein the VOC is, for example, less than 500 or even less than 400 grams per liter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of copending application Ser.No. 07/851,852, filed Mar. 16, 1992, now abandoned which is acontinuation-in-part of application Ser. No. 07/809,421, filed Dec. 17,1991, now abandoned. The disclosures of these prior applications arehereby incorporated by reference in this application in their entirety.

TECHNICAL FIELD

This invention relates to compositions which comprise water-insolublepolymers and hollow microspheres. This invention also relates toadhesive and sealant compositions, and in particular, to adhesivecompositions useful for forming a bond or weld between two polymericsurfaces. More particularly, the invention relates to such compositionswhich are characterized as low VOC solvent cements useful for bonding orwelding polymeric surfaces.

BACKGROUND OF THE INVENTION

Adhesives, often referred to as cements, glues or pastes are definedgenerally as substances capable of holding materials together by surfaceattachment. Adhesives may attach to surfaces and develop the internal orcohesive strength necessary to hold the materials together while coolingfrom liquid to solid state, while loosing solvent, or during a chemicalreaction. Many of the substances designated as adhesives may also bedesignated as caulking, potting, sealing, casting or encapsulatingcompounds when employed in a thick mass. In a more restrictive sense, tobe termed an adhesive, a substance should be a liquid or a tackysemi-solid, at least for a short period of time to contact and wet asurface, and be used in a relatively thin layer to form a useful jointcapable of transmitting stresses from one substrate to another. Thus,the term "adhesives", as used in this specification and in the claimsincludes cements, glues and pastes.

Solvent cementing is a process in which thermoplastics, usuallyamorphous, are softened by the application of a suitable solvent ormixture of solvents, and then pressed together to effect a bond. Theresin itself, after evaporation of the solvent, acts as the adhesive.Many thermoplastic substrates are easier to join effectively by solventcements than by conventional adhesive bonding. Generally, a small amountof the resin to be cemented is dissolved in a solvent to form thecement. The inclusion of the resin aids in gap filling, acceleratessetting, and reduces shrinkage and internal stresses.

Solvent cements also have been utilized to bond different plasticmaterials to each other, but in such instances, the solvent must be asolvent for both plastics. Usually in such instances, a mixture ofsolvents is used. The solvent softens (dissolves) the surface of theresin to be bonded, and the surface becomes tacky. At this point, thesurfaces are brought into contact with each other, often under pressure,and dried.

For the past twenty-five years, solvent cements have been used forjoining ABS (acrylonitrile-butadiene-styrene resin), PVC(polyvinylchloride), and CPVC (chlorinated polyvinylchloride) plasticpipe and fittings. The amount of such plastic pipe used for conveying avariety of liquids is enormous. The major uses are drain, waste, vent,sewer and potable water. Plastic pipe has continued to displace the moretraditional materials used for the same purpose such as copper, steel,galvanized metal, cast iron, lead and concrete asbestos pipe. Plasticpipe currently is the material of choice in the home, municipal, andmanufacturing industries.

Currently available solvent cements generally have a volatile organicchemicals (VOC, calculated in accordance with ASTM D-2369) of from about600 to about 750 gms/liter. As a result of this awareness, regulationsare being enacted into law by Congress and in the various states forcontrolling and setting limits for the VOC of paints, coatings and othermaterials such as solvent cements.

Plastic pipe products including solvent cements, cleaners and primershave now come under newly proposed state regulations. In California, forexample, where the first air pollution control regulations wereimplemented, the California Environmental Quality Act (CEQA) along withthe South Coast Air Quality Management District (SCAQMD) and the BayArea Quality Management District (BAAQMD) have stated that the VOCcontent of solvent cements must be dramatically reduced by Jan. 1, 1994.Thus, solvent cements as currently formulated for joining plastic pipecannot be used after Jan. 1, 1993, and unless new solvent cements can bedeveloped which meet the new standards, the use of plastic pipe willbecome obsolete.

Historically, ASTM specifications were developed and adopted by pipemanufacturers in the early 1970's. Joining materials such as solventcements were also included, and ASTM specifications were writtenspecifically for these materials. National code organizations such asUnited Plumbing Code (UPC) and the International Association of Plumbingand Mechanical Officials (IAPMO) adapted ASTM standards which werefurther adapted and included into state and local plumbing codes for thehome, building and construction industries.

In the mid 1970's a third party certification organization, the NationalSanitation Foundation International (NSF) became the recognizedauthority for testing, certifying and listing those manufacturers whovoluntarily submit their products to NSF. ASTM tests that apply toplastic pipe products are performed by NSF. The listing book publishedby the NSF entitles plastic pipe product manufacturers to use the NSFlogo or seal on their products. Many local, state and other code bodieshave written into their plumbing ordinances that plastic pipe productsmust bear the NSF seal.

The current ASTM standard which relates to ABS solvent cements is ASTMD-2235 which specifies that the ABS solvent cements will contain aminimum of 15% by weight of ABS resin and the remainder is methyl ethylketone (MEK) solvent. To have a useful product, the ABS cement typicallyutilizes 30% to 35% resin and the remainder is MEK. The purpose of usinghigher than minimum resin is to produce a product that has a suitableviscosity for application to pipes and fittings. Viscosity is measuredin centipoise, and a typical ABS cement will have a viscosity of 1000 to3000 centipoise.

The ASTM standard for PVC solvent cements is ASTM D-2564. According tothis standard, such solvent cements contain a minimum of 10% PVC resin,inert fillers, and the remainder is one or more solvents from the groupof tetrahydrofuran (THF), cyclohexanone (CYH), MEK, and acetone.

ASTM F-493 sets forth the requirements for CPVC solvent cements ascontaining a minimum of 10% CPVC resin, inert fillers, and the remainderis one or more solvents including THF, CYH, MEK and/or acetone.

All three classes of solvent cement have a high solvent to solidscontent which is believed to be necessary for a solvent cement toperform satisfactorily. The high solvent content allows for penetrationand softening of the pipe outer surface and the surface of the inside ofthe coupling. Prior to application of the cement, cleaners and/orprimers are recommended per ASTM D-2855. Most codes,require the use of acleaner or primer. Rapid evaporation of the solvents is necessary toinsure handling strength of freshly solvent cemented pipe and alsoinsuring the final cure. Cure is defined as the stage where most of thesolvents applied have evaporated leaving the solvent welded joints fusedtogether so that pressure can be successfully applied.

The need for safer and lower VOC solvent cements which are easier toapply, cost effective, and which cure within a reasonable period of timewithout the use of heat, pressure, UV light or extraordinary mechanicaldevices is paramount. The bonding or adhesive properties of the solventcements must be satisfactory for the intended use whether non-pressuredrain, waste or vent (DWV) or pressure systems used in potable waterapplications.

U.S. Pat. No. 4,687,798 describes and claims a solvent cement forjoining polymers comprising from about 10% to 15% of a water-insolublepolymer such as PVC or ABS, and a solvent comprised of ethyl acetate andN-methyl-2-pyrrolidone. U.S. Pat. No. 4,788,002 claims a similar solventcement which consists of a solution of a solvent of ethyl acetate andN-methyl-2-pyrrolidone wherein the ethyl acetate ranges from about 3% toabout 90% with the balance being N-methyl-2-pyrrolidone.

U.S. Pat. No. 4,098,719 describes polyvinyl chloride solvent weld primercompositions for use in the assembly of polyvinyl chloride pipe andfittings to themselves or to ABS pipe or fittings. The primer consistsessentially of an organic solvent containing from about 0.5 to about 2.5weight percent of an unplasticized polyvinyl chloride resin dissolved inthe solvent which is a mixture of tetrahydrofuran and dimethylformamidein a weight ratio of from about 164:1 to 1:1.

Solvent cements are also described in U.S. Pat. No. 3,765,983 which areapplied with specially-designed applicators. The solvent cements whichare described comprise a solution of a PVC, ABS or CPVC in a suitablesolvent such as tetrahydrofuran, cyclohexanone, dimethylformamide, ormixtures thereof. The resin in the cement is preferably the same as theresin of the pipe and fittings to be joined.

U.S. Pat. No. 3,770,547 relates to a method for adhesively bondingsurfaces which includes the use of adhesives including solvent cementssuch as volatile solvent solutions of polyvinylchloride, ABS polymers,cellulose acetate, etc., in organic liquid vehicles such as ethanol,methanol, methyl ethyl ketone, acetone, tetrahydrofuran, etc.

U.S. Pat. Nos. 3,230,184; 3,873,475; and 4,053,448 relate to polyesterresin compositions which contain hollow glass microspheres. Thecompositions described in the '475 patent are useful as lightweightpatching, caulking or sealing compositions, and the '448 patentdescribes the compositions as being useful patching compositions forrepairing imperfections in metal surfaces. The polyester resin moldingcompositions described in the '184 patent are reported to yield productsof substantial strength and lighter weight. The compositions alsocontain a fibrous filler material in addition to the hollow spheres.

Inorganic filler materials which comprise a mixture of an inorganicpowder and inorganic hollow microspheres are reported to be useful in acurable polyester composition in U.S. Pat. No. 5,028,456. The curablecomposition comprises, in addition to the inorganic filler, at least oneunsaturated polyester resin, at least one hydrocarbon monomercopolymerizable with the polyester, and at least one arylsulfonamide-aldehyde resin. The compositions are useful as plastic bodyfillers for repairing metal surfaces.

SUMMARY OF THE INVENTION

A composition is described with comprises a mixture of

(A) from about 5% to about 60% by weight of at least one water-insolublepolymer;

(B) from about 1% to about 30% by weight of inorganic or syntheticresinous hollow microspheres; and

(C) from about 10% to about 85% of at least one volatile organic liquidwhich is a solvent for the polymer of (A).

The compositions also may contain (D) at least one solid particulateinorganic filler. Compositions such as solvent cements prepared inaccordance with the present invention are characterized as low VOCcompositions wherein the VOC is, for example, less than 500 or even lessthan 400 grams per liter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In addition to the definitions contained in the Background, thefollowing terms utilized in the present application and claims have thefollowing meanings:

weld--to fuse or join two components together through the use of theadhesive compositions of the present invention;

solvent--a substance capable of dissolving another substance;

volatile solvent--a solvent which evaporates rapidly at room temperatureor at a slightly elevated temperature;

solvent welding--a process that utilizes solvents to join two surfacestogether;

solvent cement--an adhesive made by dissolving a plastic resin orcompound in a suitable solvent or mixture of solvents. The solventcement dissolves the surfaces of the pipe and fittings to form a bondbetween the mating surfaces provided the proper cement is used for theparticular materials and proper techniques are followed (ASTM 2235);

adhesive (composition)--includes any liquid coating composition which iscapable of forming a bond or a weld between two surfaces;

primer--conventionally employed liquid composition which prepares thesurface to be bonded for satisfactory adhesive bonding or welding;

cured--when most of the solvent applied has evaporated leaving athermoplastic solvent welded joint fused together so that pressure canbe successfully applied;

DWV--drain, waste, vent applications.

The compositions of the present invention comprise a mixture of

(A) from about 5% to about 60% by weight of at least one water-insolublepolymer;

(B) from about 1% to about 30% by weight of inorganic or syntheticresinous hollow microspheres; and

(C) from about 10% to about 85% by weight of at least one volatileorganic liquid which is a solvent for the polymer of (A).

The compositions also may, and generally do contain

(D) at least one solid particulate inorganic filler.

The compositions of the invention are useful in a variety ofapplications including use as adhesives, cements (including solventcements) glues or pastes for holding together materials by surfaceattachment, and as sealants which are load-bearing elastic jointing andinsulating materials.

(A) Water-Insoluble Polymer

The compositions of the present invention comprise at least onewater-insoluble polymer, especially those polymers which are generallyused in adhesive compositions such as epoxies, phenolics,phenol-aldehydes, urea-aldehydes, polyesters, polycarbonates,polyacrylates, polyacrylamides, polyamides, furans, polyvinyl acetates,PVCs, CPVCs, polyvinylidene fluoride (PVDF), ABS, styrene polymers,terpolymers of acrylonitrile, butadiene and α-methyl styrene, terpolymerof methyl or ethyl acrylate, butadiene and styrene, terpolymers ofacrylic esters, styrene and acrylonitrile (ASA), polymers of styrene andmaleic anhydride (SMA), styrene-acrylonitrile polymers (SAN), celluloseacetates, cellulose acetate butyrate, cellulose propionate, cellulosenitrate, polysulfones, polysulfides, polyphenylene oxides (PPO),polyetheramides, and various copolymers such as copolymers of PVC andvinyl acetate, etc. When the compositions are to be used as a solventcement, the water-insoluble polymers which are soluble in a volatilesolvent to provide an effective cement include PVC, CPVC, PVDF, ABS,polycarbonate, polystyrene, polyacrylates, cellulose acetate,polyacrylamide, polyamide, etc. Of these polymers, PVC, CPVC and ABS areof the most interest due to their widespread use. The polymer or polymermixture dissolved in the solvent to form the cement of the invention maybe freshly prepared polymer, and in some instances may be polymerregrind. Generally, the polymer or polymers in a cement are identical orat least chemically similar to the polymer surface(s) to be cemented.

The ABS polymer dissolved in the solvent to form the composition of thepresent invention generally will have a minimum butadiene content of 6%,a minimum acrylonitrile content of 15% and a minimum styrene orsubstituted styrene content of 15%. In one embodiment, useful ABS resinscontain from about 25-45% acrylonitrile, 6-15% butadiene and 40-60%styrene or substituted styrene. Useful ABS polymers are availablecommercially from General Electric, for example. Blendex ADG-21 is anABS resin from GE which is approved for use in NSF sanctioned pipeapplications, and this resin comprises about 35.4% acrylonitrile, 7.46%butadiene and 56.9% styrene. Its density is 1.02 g/cc. Blendex 211 isanother ABS resin froraGE which contains about 36.3% acrylonitrile,9.50% butadiene, and 54.1% styrene. The bulk density of Blendex 211 is1.03 g/cc.

In another embodiment, the water-insoluble resin is a vinyl chloridepolymer or copolymers including, for example, polyvinyl chloride (PVC)and chlorinated polyvinyl chloride (CPVC). Vinyl chloride polymers andcopolymers are well known in the art. Copolymers of vinyl chlorideinclude, for example, copolymers of vinyl chloride with one or morecopolymerizable monomers having at least one terminal CH₂ ═C<group suchas other vinyl halides and vinylidene halides; acrylic acid, esters ofacrylic acid such as methyl acrylate, ethyl acrylate, etc.; methacrylicacid; esters of methacrylic acid; nitriles such as acrylonitrile,methacrylonitrile, etc.; acrylamides such as methyl acrylamide, etc.;vinyl ethers such as ethyl vinyl ether; vinyl ketones; vinyl acetate;vinyl pyridine; etc. Copolymers of vinyl chloride may contain up to 50%,preferably up to 20% of the copolymerizable monomers. In one embodiment,the inherent viscosity of the PVC polymers and copolymers may range fromabout 0.30 to 1.5 and more often from about 0.30 to 0.95. PVChomopolymers and copolymers are available from a number of commercialsources. For example, a PVC homopolymer resin is available fromOccidental Chemical Corporation under the designation OXY 190 and fromB. F. Goodrich under the designation "Geon" such as Geon 110X334.Copolymers are available from Occidental Chemical Corporation under thedesignation OXY 1415 (16% bound vinyl acetate, inherent viscosity 0.37,and bulk density 0.66 g/cc) and OXY 1515 (13.8% bound vinyl acetate,inherent viscosity 0.47, and bulk density of 0.61).

The chlorinated polyvinyl chlorides (CPVC) useful in the compositions ofthis invention include chlorinated polyvinyl chloride homopolymers andcopolymers. CPVC resins useful in this invention may be prepared bychlorination of any of the polyvinyl chloride homopolymers or copolymersdiscussed above by procedures known to those skilled in the art. CPVCresins available commercially, are generally available as powders, andmay contain from about 57 to about 75% by weight of chlorine. CPVC isoften the resin of choice where its high heat deflection resistance isdesirable such as in hot water piping systems. CPVC resins useful as thewater-insoluble resin in the composition of the invention are availablecommercially from, for example, B. F. Goodrich under the tradedesignation Geon 674X571.

The compositions of the present invention generally will contain atleast 5% or 10% or 20% or 30% up to about 50% or 60% of thewater-insoluble polymers. More often, the compositions will contain fromabout 20% to about 50% by weight of the water-insoluble polymer when thepolymer is an ABS polymer. When the compositions contain PVC or CPVC,the amount of the polymer is from about 10% to about 40% by weight.

(B) Inorganic or Synthetic Resinous Hollow Microspheres

The inorganic or synthetic resinous hollow microspheres incorporatedinto the compositions of the present invention generally have a densityof less than about 0.6 g/cc and a mean diameter of less than about 200microns, more often less than about 150 microns. The compositions of theinvention will contain at least 1% and more often at least 3% by weightof the hollow microspheres and may contain up to about 10% or 20% oreven 30% by weight of the microspheres. The microspheres act as a fillerand decrease the density of the adhesive composition.

The inorganic hollow microspheres used in the present inventionpreferably are glass microspheres or microbubbles such as thosedescribed in U.S. Pat. No. 3,365,315. The walls of these microspheresare made by expanding solid glass particles at temperatures above 1000°C. to form tiny hollow spheroids having an apparent density in the rangeof about 0.14 to about 0.38 g/cc, a wall thickness of about 0.5 to 2.0microns, and an average particle size of about 60 microns. Othersuitable glassy or inorganic microspheres of synthetic fusedwater-insoluble alkali metal silicate-based glass are described in U.S.Pat. No. 3,230,184, and microspheres made of sodium silicate which areuseful in the present invention are described in U.S. Pat. No.3,030,215. Microspheres prepared from heat expanded natural mineralssuch as perlite, volcanic ash, fly ash, vermiculite, etc., also may beused but are less preferred.

Hollow glass microspheres (referred to as glass bubbles) which areuseful in the present invention are available commercially from The 3MCompany under the trade designation Scotchlite™ Glass Bubbles. Thechemical properties of these glass bubbles are reported to resemblethose of a soda-lime-borosilicate glass. Glass bubble designationC15/250 has a nominal average particle density (ASTM D-2840) of 0.15g/cc, a range of 0.12 to 0.18 g/cc and a calculated bulk density of 0.07to 0.12 g/cc. Bubble type E22/400 has a nominal average particle densityof 0.22 g/cc and a range of 0.19 to 0.25 g/cc. The bulk density of theE22/400 is in the range of 0.09 to 0.17. Other glass bubbles availablefrom 3M include K-2 glass bubbles, S60/10,000 having a nominal averageparticle density of 0.60, and B23/500 having a nominal average particledensity of 0.23. Inorganic hollow microspheres also are available fromother commercial sources such as the Philadelphia Quartz Co., ValleyForge, Pa. under the designation "Q-CEL" Inorganic microspheres;Pittsburgh Corning Corp., Pittsburgh, Pa.; Emerson & Cuming Inc.,Canton, Mass.; etc.

Organic resinous microspheres may also be utilized in the compositionsof the present invention provided they are relatively inert and notsoluble in the solvent (C). Thermoset resins generally have suchproperties. Examples include microspheres of epoxy resins;urea-formaldehyde having diameters ranging from 2-60 microns and adensity of about 0.23; phenolic resin having a density of 0.2-0.35 g/ccand diameters ranging from about 2-50 microns (available from UnionCarbide under the trade designation of phenolic "microballoons");polyvinylidene polymers and copolymers having a density of 0.03 and anaverage diameter of 25-28 microns (e.g., those commercially availablefrom Dow Chemical Company under the trade designation "Saran" dryexpanded resin-bubbles); etc. For a description of these and otherorganic resin microspheres, see U.S. Pat. No. 2,797,201.

(C) Volatile Organic Liquid Solvent

The compositions of the present invention contain at least about 10% or20%, or 30% or 50% up to about 60% or 70% or 80% or 85 % by weight of atleast one volatile organic liquid which is a solvent for thewater-insoluble polymer or polymers (A) contained in the composition.Preferably, the solvent is not a solvent for the microspheres (B). Thatis, the hollow microspheres should not dissolve in the solvent. Thevolatile organic liquid or liquid mixture used as a solvent may be anyliquid or liquids which will dissolve the water-insoluble polymerscontained in the adhesive compositions, and when the compositions are tobe used as adhesives such as solvent cements, the solvent which also ispreferably a solvent for the plastic surface or surfaces which are to bewelded or bonded together by the adhesive compositions. In addition, theorganic liquids which are used as the solvents must be volatile, thatis, it must be capable of vaporizing under a wide variety of applicationtemperature conditions. In one embodiment, a volatile solvent is onewhich is capable of vaporizing at ambient or at temperatures slightlyabove ambient temperatures. The solvents should also be selected afterconsideration of the toxicity effects and biodegradability of thesolvents.

Among the solvents which may be included in the compositions of theinvention and which have been commonly used alone or in combination foradhesive compositions are lower alcohols such as methanol, ethanol andisopropanol; ketones such as acetone, methyl ethyl ketone (MEK), methylisobutyl ketone, isophorone and cyclohexanone (CYH); esters such asmethyl acetate, ethyl acetate, ethyl formate, ethyl propionate, andbutyl acetate; halogenated solvents such as methylene chloride, ethylenedichloride, trichloroethylene; ethers such as methyl Cellosolve anddioxane; and other liquids such as tetrahydrofuran (THF), N-methypyrollidone and dimethylformamide (DMF). As noted earlier the choice ofsolvent depends upon the type of water-insoluble polymer (A) and theintended use of the composition. For example, if the composition is tobe used as a solvent cement for cementing two plastic surfaces together,the solvent or at least one solvent in a mixture should be capable ofdissolving or softening the surface of the plastic. Although any of theabove solvents may be used, it has been discovered that the preferredsolvents when the compositions of the invention are to be used assolvent cements characterized as having low VOC, the solvents preferablyare tetrahydrofuran, methyl ethyl ketone, acetone, cyclohexanone,dimethylformamide (DMF), and mixtures thereof, although DMF is no longera desirable solvent in view of its carcinogenic potential in humans.Particularly useful solvents in the compositions of the presentinvention when polymer (A) is an ABS polymer are methyl ethyl ketone andacetone. In one embodiment, acetone is preferred since it can be used toprepare adhesive compositions of the present invention characterized bydesirable viscosity and low toxicity. Mixtures of tetrahydrofuran (THF)and cyclohexanone and a mixture of THF, CYH, MEK and acetone are usefulsolvents in adhesive compositions when the water-insoluble polymer (A)is PVC. When the water-insoluble polymer (A) is CPVC, THF or mixtures ofTHF, CYH, MEK and acetone are useful solvents.

(D) Solid Particulate Inorganic Filler

In addition to the above components, the compositions may and preferablydo contain at least one solid particulate inorganic filler. The amountof filler is determined by the end use of the composition. For example,adhesive compositions may contain a small amount whereas sealants willgenerally contain larger amounts of the filler. Thus, the adhesivecompositions of the present invention may be characterized as containingfrom 0 to about 4% or even up to 5% by weight of at least one solidparticulate inorganic filler. The adhesive compositions of the presentinvention generally will contain at least about 0.1% or 0.75% by weightup to about 1.5% or 3% or 4% by weight of the solid particulateinorganic filler. The particulate inorganic fillers are inert and aregenerally included in the compositions of the present invention toimprove working viscosity and structural strength, to reduce costs,and/or to reduce the tendency of the hollow microspheres to separate andfloat to the surface of the composition (i.e., the filler helps tomaintain the beads in suspension). The tendency of the glass bubbles toseparate from a homogeneous mixture is referred to in the industry as"bead float-out".

The solid particulate inorganic fillers incorporated into the adhesivecompositions of the present invention preferably are fine powders havingan average particle size of less than about 50 microns and a density ofless than about 4 g/cc. The inorganic fillers which can be utilized inthe adhesive compositions of the present invention include amorphoussilica, silica flour, ground quartz, talc, magnesium silicate, calciumcarbonate, clay, whiting, shell flour, wood flour, alumina, antimonytrioxide, asbestos powder, barium sulfate, calcined clays, China clays,magnesium oxide, mica powder, fumed silica, etc. A preferred filler isfumed silica available commercially from Cabot Corporation under thetrade designation CAB-O-SIL and from the Degussa Corporation under thetrade designation Aerosil. For example, CAB-O-SIL grade PTG is a fumedsilica available from the Cabot Corporation and having a surface area of200±25 m² /g and a nominal particle diameter of 0.014 microns.

The compositions of the present invention should be thoroughly blendedto provide substantially homogeneous mixtures. Substantially homogeneousmixtures are desirable since non-uniform mixtures will result innon-uniform distribution of the adhesive composition and non-uniformadhesion to substrate surfaces. If desired, small amounts of pigments orcolorants such as titanium dioxide, carbon black or a dye or othercolorant may be added to the adhesive compositions to serve as a guidefor uniform mixing and to provide a method of identifying variousadhesive compositions. In one embodiment, it is desirable to dispersethe solid particulate inorganic filler into the polymer prior toaddition of the hollow microspheres. For example, good results areobtained when the filler is dispersed into the polymer using a highspeed Cowles type impeller.

The adhesive compositions formulated in accordance with the presentinvention generally have a minimum viscosity of about 500 centipoises(cps), and the viscosity may be as high as 10,000 to 15,000 cps providedthat the adhesive compositions can be readily applied to the surfaces tobe bonded. The molecular weights of the polymers (A) affect theviscosity of the adhesive composition. The use of polymers having lowerinherent viscosities permits a higher polymer percentage or loading andthereby lower the amount of solvent required to achieve a givenviscosity. Viscosities may range from about 8000 to about 15,000 cps andare readily obtained with the compositions of the present invention, andsuch viscosities are desirable since the adhesive may be applied tosubstrates without dripping and with little or no spillage. The adhesivecompositions of the invention appear to form a "pseudo skin" whichprevents the adhesive compositions from dripping once applied to asubstrate.

The compositions of the present invention are easy to apply, costeffective, and cured within a reasonable period of time without the useof heat, pressure, UV light or extraordinary mechanical devices. Thebonding or adhesive properties are satisfactory for the intended useswhether non pressure drain, waste, vent (DWV), applications or pressuresystems used in potable water applications. One particular advantage ofthe adhesive compositions of the present invention is that thecompositions are a one-component system and are "plumber friendly".

The compositions of the present invention are characterized as lower VOCcompositions than similar compositions not containing the hollowmicrospheres. For example, the adhesive compositions of the presentinvention may also be characterized as lower VOC compositions than thepresently available solvent cements. The use of the compositions of thepresent invention results in a reduction in organic emissions due to theuse of a combination of lower VOC compositions, application methods(less waste), and the non-use of either cleaners or primers to achievesatisfactory results in bonding surfaces such as ABS and PVC pipe andfittings.

In accordance with the present invention, compositions can be preparedhaving desirable VOC limits by varying the amounts of the components,and in particular, through the use of the hollow microspheres such asthe glass bubbles described above. The use of the inorganic hollowmicrospheres is desirable because they are chemically stable,water-insoluble, non-hazardous (non-toxic), of high strength, and theyare compatible with the other ingredients used in the adhesivecompositions. In accordance with the present invention, usefulcompositions can be prepared which may be characterized as low VOCcompositions, and more particularly, adhesives characterized by VOC's ofless than 500 and even less than 300 grams per liter.

The following examples illustrate the compositions of the presentinvention. Unless otherwise indicated in the following examples andelsewhere in the specification and claims, all parts and percentages areby weight.

EXAMPLE 1

    ______________________________________                                        ABS resin (ADG-21)       40%                                                  Methyl ethyl ketone      56%                                                  E-22 glass bubbles       4%                                                   ______________________________________                                    

EXAMPLE 2

    ______________________________________                                        ABS resin (Blendex 211)  40%                                                  Methyl ethyl ketone      56%                                                  E-22 glass bubbles       4%                                                   ______________________________________                                    

EXAMPLE 3

    ______________________________________                                        ABS resin (Blendex 211)  40%                                                  Methyl ethyl ketone      56%                                                  K-2 glass bubbles        4%                                                   ______________________________________                                    

EXAMPLE 4

    ______________________________________                                        ABS resin (Blendex 211)  40%                                                  Methyl ethyl ketone      56%                                                  C-15 glass bubbles       4%                                                   ______________________________________                                    

EXAMPLE 5

    ______________________________________                                        ABS resin (Blendex 211)  38%                                                  Methyl ethyl ketone      56%                                                  E-22 glass bubbles       6%                                                   ______________________________________                                    

EXAMPLE 6

    ______________________________________                                        ABS resin (Blendex 211)  36%                                                  Methyl ethyl ketone      56%                                                  E-22 glass bubbles       8%                                                   ______________________________________                                    

EXAMPLE 7

    ______________________________________                                        ABS resin (Blendex 211)  40%                                                  Methyl ethyl ketone      50%                                                  E-22 glass bubbles       10%                                                  ______________________________________                                    

EXAMPLE 8

    ______________________________________                                        ABS resin (Blendex 211)  34%                                                  Methyl ethyl ketone      56%                                                  E-22 glass bubbles       10%                                                  ______________________________________                                    

Some of the characteristics of the compositions of Examples 2-8 aresummarized in the following Table I.

                  TABLE I                                                         ______________________________________                                        Example                                                                              Viscosity (cps).sup.1                                                                       Wt. (lbs)/gal                                                                            VOC (g/l)                                     ______________________________________                                        2      7060          6.53       438                                           3       10,000+      6.11       410                                           4       10,000+      6.02       404                                           5      7060          6.21       416                                           6      7500          5.83       391                                           7      10,000        5.51       370                                           8      7100          5.56       373                                           ______________________________________                                         .sup.1 ASTM D2235                                                        

EXAMPLE 9

    ______________________________________                                        ABS resin (Blendex 200)  37%                                                  Methyl ethyl ketone      56.25%                                               E-22 glass bubbles       6%                                                   Talc                     0.75%                                                ______________________________________                                    

EXAMPLE 10

    ______________________________________                                        ABS resin (Blendex 211)  37%                                                  Methyl ethyl ketone      56%                                                  E-22 glass bubbles       6%                                                   PTG                      1%                                                   ______________________________________                                    

EXAMPLE 11

    ______________________________________                                        ABS resin (Blendex 211)  35%                                                  Methyl ethyl ketone      56%                                                  E-22 glass bubbles       8%                                                   PTG                      1%                                                   ______________________________________                                    

EXAMPLE 12

    ______________________________________                                        ABS resin (Blendex 211)  34%                                                  Methyl ethyl ketone      56%                                                  E-22 glass bubbles       9%                                                   PTG                      1%                                                   ______________________________________                                    

EXAMPLE 13

    ______________________________________                                        ABS resin (Blendex 211)  35%                                                  Acetone                  56%                                                  E-22 glass bubbles       8%                                                   PTG                      1%                                                   ______________________________________                                    

EXAMPLE 14

    ______________________________________                                        ABS resin (Blendex 211)  39%                                                  Acetone                  56%                                                  E-22 glass bubbles       4%                                                   PTG                      1%                                                   ______________________________________                                    

EXAMPLE 15

    ______________________________________                                        ABS resin (Blendex 211)  37%                                                  Acetone                  56%                                                  E-22 glass bubbles       6%                                                   PTG                      1%                                                   ______________________________________                                    

EXAMPLE 16

    ______________________________________                                        ABS resin (Blendex 211)  37%                                                  Acetone                  53.85%                                               E-22 glass bubbles       8%                                                   PTG                      1.15%                                                ______________________________________                                    

EXAMPLE 17

    ______________________________________                                        ABS resin (Blendex 211)  33%                                                  Acetone                  55.75%                                               E-22 glass bubbles       10%                                                  PTG                      1.25%                                                ______________________________________                                    

EXAMPLE 18

    ______________________________________                                        ABS resin (Blendex 211)  30.25%                                               Acetone                  51%                                                  E-22 glass bubbles       17.25%                                               PTG                      1.5%                                                 ______________________________________                                    

EXAMPLE 19

    ______________________________________                                        ABS resin (Blendex 211)  37%                                                  Methyl ethyl ketone      53.8%                                                E-22 glass bubbles       8%                                                   PTG                      1.15%                                                ______________________________________                                    

EXAMPLE 20

    ______________________________________                                        PVC resin (Geon 110X334) 16.44%                                               THF                      45.67%                                               CYH                      11.01%                                               MEK                      0.15%                                                Acetone                  11.51%                                               E-22 glass bubbles       13.20%                                               PTG                      2.02%                                                ______________________________________                                    

EXAMPLE 21

    ______________________________________                                        PVC resin (Geon 110X334) 18.0%                                                THF                      53.0%                                                CYH                      12.0%                                                E-22 glass bubbles       15.0%                                                PTG                      2.0%                                                 ______________________________________                                    

EXAMPLE 22

    ______________________________________                                        CPVC resin (Geon 674X571)                                                                              16.56%                                               THF                      51.04%                                               CYH                      6.00%                                                MEK                      9.86%                                                Acetone                  0.16%                                                E-22 glass bubbles       12.05%                                               PTG                      2.63%                                                Orange dye               0.70%                                                Tin stabilizer           1.00%                                                ______________________________________                                    

EXAMPLE 23

    ______________________________________                                        CPVC resin (Geon 674X571)                                                                              13.68%                                               THF                      68.50%                                               E-22 glass bubbles       14.14%                                               PTG                      1.65%                                                Orange dye               0.74%                                                Tin stabilizer           1.29%                                                ______________________________________                                    

EXAMPLE 24

    ______________________________________                                        CPVC resin               12.35%                                               THF                      51.68%                                               CYH                      9.53%                                                MEK                      0.51%                                                Acetone                  17.93%                                               E-22 glass bubbles       4.03%                                                PTG                      2.50%                                                Orange dye               0.46%                                                Tin stabilizer           1.01%                                                ______________________________________                                    

Some of the properties and characteristics of the compositions ofExamples 10-18 and 20-23 are summarized in the following Table II.

                  TABLE II                                                        ______________________________________                                        Example                                                                              Viscosity (cps).sup.1                                                                       Wt. (lbs)/gal                                                                            VOC (g/l)                                     ______________________________________                                        10     10,000+       6.24       419                                           11     10,000+       5.91       397                                           12     10,000+       5.66       380                                           13     7500          5.90       396                                           14     8600          6.80       456                                           15     9300          6.28       405                                           16     9500          5.90       380                                           17     11,600        4.90       327                                           18     14,000        4.65       284                                           20     10,000+       5.30       434                                           21     10,000+       5.25       400                                           22     10,000+       5.60       450                                           23     10,000+       5.28       433                                           ______________________________________                                         .sup.1 ASTM D2235                                                        

The utility of the compositions of the present invention, and inparticular, the utility of the adhesive compositions as solvent cementsfor ABS pipes and fittings is demonstrated by testing the adhesivecomposition for lap shear strength after 48 hours in accordance withASTM D-2235. ASTM D-2235 requires lap shear values of 800 psi after 48hours but no values are given for hydrostatic burst since thisspecification is for DWV applications only. Hydrostatic quick burststrength tests are conducted per ASTM D-2564 (normally for PVC) usingABS pipe and couplings. There is no hydrostatic burst requirement onsolvent cemented ABS pipe and couplings. The results of these testsconducted with the adhesive compositions of Examples 13-19 aresummarized in the following Table III. For comparison, a standard ABScement formulated to meet ASTM D-2235 and comprising 33% by weight ofABS resin and 67% of methyl ethyl ketone (Control-1) is also tested andthese results are reported in Table III.

                  TABLE III                                                       ______________________________________                                        Test Results                                                                                Lap Shear.sup.1                                                                         Hydrostatic Burst                                     Adhesive Example                                                                            (psi/48 hrs)                                                                            (psi)                                                 ______________________________________                                        13            710       Pipe burst at 320                                     14            830       Pipe burst at 300                                     15            780       Pipe burst at 310                                     16            701       Pipe burst at 320                                     17            590       Pipe burst at 290                                     18            255       End cap broke at 290                                  Control-1     800       .sup. Pipe burst at 270.sup.2                         ______________________________________                                         .sup.1 Average of 5 replications per example.                                 .sup.2 Considerable swelling of pipe prior to bursting.                  

The utility of the adhesive compositions containing ABS resin as solventcements for PVC pipes and fittings is demonstrated by testing theadhesive composition of Examples 14, 16 and 19 on PVC to PVC parts perASTM D-2564. The lap shear strengths after 24 and 48 hours weredetermined and the results (average of 5 replications per example) aresummarized in Table IV.

                  TABLE IV                                                        ______________________________________                                        Test Results                                                                                  Lap Shear (psi)                                               Adhesive Example  24 hrs. 48 hrs.                                             ______________________________________                                        14                500     520                                                 16                425     430                                                 19                600     640                                                 ______________________________________                                    

As can be seen, maximum lap shear values occur at the 24-hour interval.When methyl ethyl ketone is used as the sole solvent, higher lap shearvalues are observed.

Hydrostatic burst tests are performed on both two-inch Schedule 40 andSchedule 80 PVC assemblies per ASTM D-2564. The 24-hour results arereported in Table V.

                  TABLE V                                                         ______________________________________                                        Adhesive Example Schedule Burst (psi)                                         ______________________________________                                        16               40       540                                                 19               40       660                                                 16               80       680                                                 19               80       890                                                 ______________________________________                                    

During application of solvent cement using the standard dauber includedwith the can of cement, some solvent is lost during application throughdrippings, evaporation, excess cement on outer pipe, and residual cementleft in the can. All of these factors contribute to VOCs emitted intothe atmosphere. The benefits of the adhesive composition of thisinvention in reducing VOC emissions are demonstrated in a series ofexperiments using two control cements (Control-1 and Control-2) and anadhesive of the invention as represented by Example 16. Theseformulations are as follows. Control-1 is a current standard ABS cement.

    ______________________________________                                        Control-1                                                                     ABS resin                33%                                                  Methyl ethyl ketone      67%                                                  Control-2                                                                     ABS resin                45%                                                  Acetone                  55%                                                  Example 16                                                                    ABS resin                37%                                                  Acetone                  53.85%                                               E-22 glass bubbles       8%                                                   PTG                      1.15%                                                ______________________________________                                    

ABS two-inch pipe and end cap(s) meeting ASTM D-2661 are used. Thepurpose for two end caps on one five-inch piece of pipe is to show VOCstrapped within the piping system closely simulating in-fieldinstallations.

Four replications per each formula per one or two end capped pipe areused. The temperature during the test is 72° F.±1° F. Evaporation ofVOCs and cement loss are recorded. The can is weighed before and aftereach application. Immediate cement loss from spillage, dripping andevaporation are measured, and then the VOCs evaporating from the jointafter 15, 30 and 60-minute intervals and at 1, 2, 4, 8, 24, 48, 72, 96and 168 hours (7 days) are recorded. Using a one-pint can of formula,the formulations are applied with the dauber in the can using standardapplication techniques as used by plumbers in the field per ASTM D-2855.The data and results are summarized in Table VI.

                  TABLE VI                                                        ______________________________________                                                     Control-1                                                                             Control-2 Example 16                                     ______________________________________                                        One Cap                                                                       Total cement applied/                                                                        13.75     8.162     3.825                                      joint (gms)                                                                   Total cement on assembly/                                                                    6.14      6.17      3.545                                      joint (gms)                                                                   Total waste (gms)                                                                            7.61      2.00      0.280                                      (% loss)       (55.34)   (24.40)   (7.32)                                     Two Cap                                                                       Total cement applied/                                                                        13.31     7.265     3.573                                      joint (gms)                                                                   Total cement on assembly/                                                                    5.245     5.82      3.242                                      joint (gms)                                                                   Total waste (gms)                                                                            8.065     1.445     0.330                                      (% loss)       (60.6)    (20)      (9.23)                                     ______________________________________                                    

The data summarized in Table VI demonstrate the reduction in waste whenusing the adhesive of this invention (Example 16). This reduction inwaste represents a significant reduction in costs and VOC emissions.

The results of the tests conducted to determine the amount of VOCevaporating from the ABS joints bonded with the three cements aresummarized in Table VII.

                  TABLE VII                                                       ______________________________________                                        Two Cap        Control-1 Control-2 Example 16                                 ______________________________________                                        Cement on assembly (g)                                                                       5.245     5.820     3.242                                      Cement after*                                                                 15 min.        4.505     5.42      3.106                                      30 min.        4.363     5.28      3.053                                      45 min.        4.342     5.205     3.024                                      60 min.        4.28      5.13      2.998                                       2 hrs.        4.237     5.055     2.95                                        4 hrs.        4.196     4.94      2.904                                       8 hrs.        4.122     4.83      2.859                                      24 hrs.        4.127     4.765     2.843                                      48 hrs.        4.09      4.726     2.82                                       72 hrs.        4.038     4.696     2.81                                       Total Loss                                                                    grams          1.206     1.123     0.431                                      %              23        19        13.3                                       ______________________________________                                         *Average of 8 replications (8 caps4 pipes)                               

The reduction in VOCs emitted from the cemented assemblies furtherdemonstrates the advantage of the adhesive of the invention.

While the invention has been explained in relation to its preferredembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications as fall withinthe scope of the appended claims.

I claim:
 1. A composition comprising a mixture of(A) from about 5% toabout 60% by weight of at least one water-insoluble polymer selectedfrom acrylonitrile-butadiene-styrene polymer, polyvinyl chloride,chlorinated polyvinyl chloride or mixtures thereof; (B) from about 1% toabout 30% by weight of glass or synthetic resinous hollow microspheres;(C) from about 10% to about 85% by weight of at least one volatileorganic liquid which is a solvent for the polymer of (A); and (D) fromabout 0.1% to about 5% by weight of at least one solid particulateinorganic filler.
 2. The composition of claim 1 wherein the hollowmicrospheres (B) are hollow glass microspheres.
 3. The composition ofclaim 1 wherein the solvent (C) comprises methyl ethyl ketone, acetone,tetrahydrofuran, cyclohexanone or mixtures of two or more thereof. 4.The composition of claim 1 wherein the polymer is anacrylonitrile-butadiene styrene polymer and the solvent (C) comprisesacetone, methyl ethyl ketone, or a mixture thereof.
 5. The compositionof claim 1 wherein the polymer is a polyvinyl chloride or chlorinatedpolyvinyl chloride polymer and the solvent (C) comprisestetrahydrofuran.
 6. The composition of claim 1 wherein the filler isfumed silica.
 7. An adhesive composition comprising a mixture of(A) fromabout 5% to about 60% by weight of at least oneacrylonitrile-butadiene-styrene polymer; (B) from about 1% to about 30%by weight of glass or synthetic resinous hollow microspheres; and (C)from about 10% to about 85% by weight of at least one volatile organicliquid which is a solvent for the polymer of (A).
 8. The adhesivecomposition of claim 7 wherein the hollow microspheres (B) are hollowglass microspheres.
 9. The adhesive composition of claim 7 wherein thehollow microspheres (B) comprise soda-lime-borosilicate glass.
 10. Theadhesive composition of claim 7 containing from about 3% to about 10% byweight of the hollow microspheres (B).
 11. The adhesive composition ofclaim 7 wherein the hollow microspheres (B) have an average particledensity of from about 0.1 to about 0.6 g/cc and a mean diameter of lessthan about 150 microns.
 12. The adhesive composition of claim 7 whereinthe volatile organic liquid (C) is methyl ethyl ketone, acetone,tetrahydrofuran, cyclohexanone or mixtures thereof.
 13. The adhesivecomposition of claim 7 also containing 0.1% up to about 4% by weight ofat least one solid particulate inorganic filler.
 14. The adhesivecomposition of claim 13 wherein the filler is fumed silica.
 15. Anadhesive composition comprising a mixture of(A) from about 10% to about60% by weight of at least one acrylonitrile-butadiene-styrene polymer;(B) from about 1% to about 20% by weight of inorganic or syntheticresinous hollow microspheres; and (C) from about 20% to about 85% of atleast one volatile organic liquid which is a solvent for the polymer of(A).
 16. The adhesive composition of claim 15 wherein the hollowmicrospheres (B) have an average particle density of from about 0.1 toabout 0.6 g/cc and a mean diameter of less than about 150 microns. 17.The adhesive composition of claim 15 wherein the solvent (C) is methylethyl ketone, acetone, tetrahydrofuran, cyclohexanone, or mixturesthereof.
 18. The adhesive composition of claim 15 also containing(D) atleast one solid particulate inorganic filler.
 19. The adhesivecomposition of claim 18 wherein the filler is fumed silica.
 20. Anadhesive composition for forming a bond or weld between twoacrylonitrile-butadiene-styrene polymer or polyvinyl chloride surfacescomprising a mixture of(A) from about 30% to about 50% by weight of anacrylonitrile-butadiene-styrene resin; (B) from about 3% to about 10% byweight of hollow glass microspheres having an average particle densityof from about 0.1 to about 0.4 g/cc; (C) from about 50% to about 60% byweight of acetone or methyl ethyl ketone or mixtures thereof; and (D)from about 0.75% to about 1.5% by weight of at least one solidparticulate inorganic filler having an average particle size of lessthan about 50 microns.
 21. The adhesive composition of claim 20 whereinthe composition has a VOC is less than about 500 gms/liter.
 22. Theadhesive composition of claim 20 wherein (C) is acetone.
 23. A method ofadhesively bonding or welding a first plastic surface to a secondplastic surface which comprises the steps of(I) applying a compositioncomprising a mixture of(A) from about 5% to about 60% by weight of atleast one water-insoluble polymer; (B) from about 1% to about 30% byweight of glass or synthetic resinous hollow microspheres; and (C) fromabout 10% to about 85% by weight of at least one volatile organic liquidwhich is a solvent for the polymer of (A) to the first surface or thesecond surface, or both surfaces; (II) contacting the first surface withthe second surface; and (III) allowing the adhesive composition to forma bond or weld between the first surface and the second surface.
 24. Themethod of claim 23 wherein the composition applied in step (I) alsocontains (D) from about 0.1 to about 5% by weight of at least one solidparticulate inorganic filler.
 25. The method of claim 23 wherein thepolymer (A) in the composition applied in step (I) comprisesacrylonitrile-butadiene-styrene, polyvinyl chloride, chlorinatedpolyvinyl chloride or mixtures thereof.
 26. A method of adhesivelybonding or welding a first plastic surface to a second plastic surfacewhich comprises the steps of(I) applying a composition comprising amixture of(A) from about 10% to about 60% by weight of at least onewater-insoluble polymer selected from acrylonitrile-butadiene-styrenepolymer, polyvinyl chloride, chlorinated polyvinyl chloride or mixturesthereof; (B) from about 1% to about 20% by weight of glass or syntheticresinous hollow microspheres; and (C) from about 20% to about 70% byweight of at least one volatile organic liquid which is a solvent forthe polymer of (A) to the first surface or the second surface, or bothsurfaces; (II) contacting the first surface with the second surface; and(III) allowing the adhesive composition to form a bond or weld betweenthe first surface and the second surface.
 27. The method of claim 26wherein the first surface is the inner surface of a plastic fitting, andthe second surface is the outer surface of a plastic pipe wherein theplastic is a polyvinyl chlorinated, chlorinated polyvinyl chloride oracrylonitrile-butadiene-styrene polymer.
 28. The method of claim 26wherein the composition also contains(D) at least one solid particulateinorganic filler.
 29. The method of claim 28 wherein the filler is fumedsilica.
 30. The method of claim 26 wherein the polymer is anacrylonitrile-butadiene-styrene resin, and at least one of the plasticsurfaces is a polyvinylchloride or acrylonitrile-butadiene-styreneplastic surface.
 31. The method of claim 26 wherein the polymer (A) isacrylonitrile-butadiene-styrene, and the volatile organic liquid (C) isacetone or cyclohexanone.